I can't believe that the Chelsea team is stronger than Dortmund. At least their performance doesn't seem like it. Chelsea's last team performance is very poor. Chelsea has lost points in their last 5 Premier League matches. They are not able to play well. The performance of their forward players is very poor. So I see no reason to think that Chelsea will easily win against Dortmund. Dortmund has a strong squad. And they are capable of beating any team. So Dortmund vs Chelsea match will be very competitive and both teams have a chance to win.
The champions league knock out tie will take place after the worldcup; so it is difficult to judge the players and the team using their pre worldcup performances and form; because by the time club football resumes; alot would have changed (including outgoing or incomings of new signing). I think chelsea will edge through dortmund and qualify